For severe sarcopenia, the RCS curve (Figure 2C) revealed a cutoff at log CRP = 0.489 separating the plots into two phases, with severe sarcopenia risk decreasing slightly for log CRP < 0.489 (OR: 0.82, 95% CI: 0.70–0.98) and increasing rapidly for log CRP > 0.489 (OR: 2.31, 95% CI: 1.94–2.74). The gene discussed is CRP; the disease is sarcopenia.